The present disclosure relates to an exhaust gas cleaning apparatus for cleaning exhaust gas that is discharged from an internal combustion engine.
An exhaust gas cleaning apparatus, that is mounted on a vehicle, captures particulate matter (PM) contained in the exhaust gas that is discharged from an internal combustion engine of the vehicle using a diesel particulate filter (DPF) unit. A capturing capacity of the DPF unit may be limited. Therefore, when the amount of PM accumulated in the DPF unit exceeds a predetermined limit, a DPF regeneration process needs to be performed by increasing the temperature of the exhaust gas to a level at which PM combusts to thereby remove the accumulated PM from the DPF unit.
Meanwhile, ash which is derived from engine oil components and contained in the exhaust gas also accumulates in the DPF unit during operation of the vehicle. Ash is decomposed at temperatures exceeding 1,000° C. Therefore, ash is not removed from the DPF unit during a normal DPF regeneration process and continues to accumulate in the DPF unit. In order to prevent the accumulation of an excessive amount of ash and the clogging of the DPF unit due to the accumulated ash, the DPF unit needs to be cleaned or replaced periodically.
According to the exhaust gas cleaning apparatus mentioned by Japanese Unexamined Patent Application Publication No. 2010-19188, for example, handles are provided on an outer peripheral surface of the DPF casing that is connected between an upstream side exhaust pipe and a downstream side exhaust pipe. During maintenance of the DPF unit, a worker utilizes the handles to remove the DPF unit from the upstream side exhaust pipe and the downstream side exhaust pipe.
Based on size constraints of the vehicle, various components of the exhaust gas cleaning apparatus and various components of the internal combustion engine are commonly arranged in the vicinity of the DPF unit, and as such the DPF unit is capable of being heated to a high temperature. Therefore, there is a need to prevent thermal damage to such components caused by heat that is radiated from the heated DPF unit.
To reduce heat damage, it may be contemplated to provide a thermal insulator on the outer peripheral surface of the DPF casing. However, in the case of an exhaust gas cleaning apparatus having handles like the apparatus mentioned in the above-mentioned publication, it is difficult to cover the entire outer peripheral surface of the DPF casing due to the presence of the handles.
The present disclosure is directed to providing an exhaust gas cleaning apparatus which is configured to permit easy removal of the DPF unit from the upstream side exhaust pipe and the downstream side exhaust pipe and which is capable of reducing thermal damage due to heat radiation of the DPF unit.